[Bug libstdc++/29286] [4.0/4.1/4.2/4.3 Regression] placement new does not change the dynamic type as it should

[gdr at cs dot tamu dot edu]

------- Comment #103 from gdr at cs dot tamu dot edu  2007-05-18 22:16 -------
Subject: Re:  [4.0/4.1/4.2/4.3 Regression] placement new does not change the
dynamic type as it should

"pcarlini at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:

| ------- Comment #98 from pcarlini at suse dot de  2007-05-18 21:27 -------
| (In reply to comment #97)
| > First and foremeost, we have to generate correct code.  If that means
| > the memory barrier solution, for now, then so be it.
| 
| Yes, but I'm a little worried myself not by <memory> but by containers like
| <list>, <map> and <set>, where we call allocator::contruct, which uses
| placement new, to "install" the value in the allocated node. In that case,
| unfortunately, per 20.4.1.1/12, we can't optimize it for POD types :( At
| minimum we should benchmark a bit...

If the element type is a POD, we should use assignment, not placement new.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29286